Researchers at the University of North Carolina began testing soaps after local nurses noticed an unusual uptick in positive drug tests on infants. Their conclusions, first relayed to the journal’s online subscribers in March, may have far-ranging implications for any government agency or corporation that has used drug testing on citizens or employees.

Researchers were also able to trigger false positive results for marijuana with common hospital gel soap and several other products, which led them to discover that two specific chemical compounds can completely confound commonly used immunoassay drug tests and produce false positives for marijuana.

They specifically highlighted the ingredients polyquaternium 11 and cocamidopropyl betaine as “showing strong reactivity” with chemicals in less expensive drug tests, producing the positive result for marijuana. Researchers added that less than 0.1 mililiters of these chemicals in a drug test sample could contaminate the results.

The chemicals are not in any way related to marijuana and both are used in hundreds of products like toothpaste, shampoo, makeup, hair dye and household cleaning agents. In other words, it would not be surprising to find trace amounts of these products in urine, saliva or hair follicles — putting a huge question mark on the validity of less expensive drug tests conducted by employers and law enforcement agencies around the nation.

“Given these consequences, it is important for laboratories and providers to be aware of this potential source for false positive screening results and to consider confirmation before initiating interventions,” the study’s authors concluded. “Most importantly, we demonstrate the need for active involvement in the ‘total testing process,’ as sources of error are not confined to the laboratory walls.”

“The lesson from this study is two-fold,” Paul Armentano, deputy director of the National Organization for the Reform of Marijuana Laws (NORML), explained to Raw Story in an email exchange. “One, immunoassay drug test results must always be confirmed. (FYI: Immunoassay tests for a chemical reaction, not the actual drug itself or its metabolite, which is why false positives on these tests are common.) And [two], standard drug tests provide society with very little useful information regarding whether someone actually used a particular substance, when they last used a particular substance, or whether they were impaired at the time they were tested. Only in an environment of criminal drug prohibition can people judged solely on the contents of their urine, rather than on their behavior and performance.”
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About the Author

Stephen C. Webster is the senior editor of Raw Story, and is based out of Austin, Texas. He previously worked as the associate editor of The Lone Star Iconoclast in Crawford, Texas, where he covered state politics and the peace movement’s resurgence at the start of the Iraq war. Webster has also contributed to publications such as True/Slant, Austin Monthly, The Dallas Business Journal, The Dallas Morning News, Fort Worth Weekly, The News Connection and others. Follow him on Twitter at @StephenCWebster.